The present invention relates to the field of gas plasma treating and pertains particularly to a system and method of uniform plasma treatment of articles.
Gas plasma etching has been found to be quite useful for many applications in the electronics and micro-circuit industry. Among the uses are such as that disclosed in U.S. Pat. No. 4,012,307 issued Mar. 15, 1977 to Eugene Phillips and assigned to the assignee hereof. In that patent there is disclosed a method of plasma etching of certain multi-layered printed circuit or wiring boards to remove smears of thin layers or coatings of plastic within drilled holes in the circuit board. The coatings of plastic and adhesive around the apertures in such boards can prevent the achievement of good contact between layers within the board during the plating or formation of contacts within the board. Plasma etching has been found to be an effective technique for the removal of these interfering layers and small fragments of plastic or the like that may remain in the apertures to interfere with effective contact.
The above identified U.S. Pat. No. 4,012,307 discloses a method of plasma etching as discussed above and the contents of said patents are fully incorporated herein by reference as though fully set forth.
Among the utility described in the aforementioned patent is that of cleaning smears and fragments of adhesive and plastic from drilled holes within multi-layered circuit boards. Although the aforementioned method is effective for this purpose it has been during use thereof that certain drawbacks do exist. For example, it has been discovered that the placement of multiple parts within an etching chamber can result in some parts being etched at a different rate from other parts. Such etching can be dependent upon the arrangement of the part within the etching chamber and its relationship or position therein relative to other similar parts. This non-uniform etching of the parts can result in over etching of certain portions of certain parts and under etching of others.
For the above reasons, it is desirable that a method and system be available which is capable of providing uniform etching of parts within a gas plasma system.